Rescuing an Old System with Semicustom Firmware

Success! Modified firmware revives legacy system. 

A customer recently presented us with a common problem: He needed new serial displays for an old system. The catch was that the new displays had to perfectly emulate the old, long-discontinued displays because the legacy system could not be reprogrammed.

He had auditioned several currently available serial displays with varying success. Our GLO-216Y was the best display overall, but its instruction set didn't match the existing setup. Could I help?